Convertible ram-jet pulse-jet engine



Feb- 26, 1963 R. A. HANsl-:L

CONVERTIBLE RAM-JET PULSE-JET ENGINE Filed Sept. 4, 1959 BY WWW @N www om N m mm; w vn.

United States Patent Oiihce 3,078,660 Paten-'ted F el). 26,' 1963' 3,078,669 CONVERHBLE RAM-JET PULSE-JET ENGINE Richard Adams Hansel, 105 Stratford Ave., Garden City, N.Y. Filed Sept. 4, 1959, Ser. No. 838,691 Z Claims. (Cl. 60-35.6)

This invention relates to jet engines and more particularly to an engine which may be operated in either the pulse-jet or ram-jet con'liguration.

It is well known that performance of a ram-jet engine depends upon the intake of high-velocity air. These engines are accordingly bu-rdened by the need for an auxiliary power source to accelerate the rain jet up to those speeds which are necessary for its operation.

'On the other hand, the pulse-jet engine has high performance capabilities for static and lou/velocity speeds but its performance deteriorates as operating speed increases.

It is thus evident that these two engines are best suited for opposite ends of the speed spectrum andl it accordingly has been proposed to provide a combination pulse jet and ram jet so that the performance capabilities of one may complement the other to extend the range of operation of the composite unit.

The various prior art attempts to accomplish the above objective are characterized by cumbersome and complicated structures which involve, for example, the placing of a pulse-jet engine inside a ram jet or by varying the overall physical configuration of the pulse jet so as to convert it into a ram jet.

In view of the fundamental requirement of reliability which is demanded by the aviation industry, it may be readily understood that these prior art attempts have met with little success. While thev pulse-jetv engine is in itself a relatively simple device, each time the prior art has attempted to convert it into a ram jet, an involved and complicated structure has resulted.

ln contrast, the present invention provides a simple jet engine configuration which is capable of being converted yfrom pulse jet to ram jet or vice versa, with an essentially simple arrangement of parts having inherent durability .and reliability.

It is accordingly an object of the invention to provide a jet engine which may be converted from a pulsing or resonant mode of operation to a ram or continuous mode of operation by the displacement of one basic engine control unit which serves either of two functions according to whether the engine is operating as a pulse jet or a ram jet.

This and other objects and advantages of the invention will be set forth in part hereinafter and in part will be obvious herefrom, or may be learned by practice with the invention, the same being realized and attained by means of the instrumentalities and combinations pointed out in the appended claims.

The invention consists of the novel parts, constructions, arrangements, -combinations and improvements herein shown and described,

-An engine embodying the principles of the invention in an exemplary manner is disclsed in the figures, of which:

FIG. 1 is a side view partially schematic and partially in cross section of the convertible jet engine; and

FIG. 2 is a front View of the control element which functions as in inlet Valve in the pulse-jet configuration and as a flame holder in the ram-jet conliguration.

Serving as the nacelle for the jet engine of FIGURE l is the housing itl, generally cylindrical in shape and having an intake il and an exhaust aperture 4t) to the right of the assembly. The arrow A indicates the relative motion of the air entering the intake. at 11. The thrust is accordingly directed in the opposite direction.'

Just aft of the intake 11 is the diffusion cham-ber 12' which is given an annular configuration by virtue of the' curved constriction 13 and the coaxial centerbody 50.' Near the aft end of the engine is the combustion section" 14 and the exhaust section 15. Exhaust section 15 kmayv include a converged `region shaped from the constric-l tion 15.

The precise Variation in cross-section of the engine is a matter of design andv depends upon the desired perform- .ance characteristics of the engine. Accordingly, the gen-v eral shape indicated in the ligure is intende-d to be exemplary only.

Located just -aft of the diffusion section 12 is a spiderl arrangement comprising a hub 17 and struts 17a, prefer'-Y ably three in number. Axially disp-laced and aligned wit-h this spider arrangement is asecond spider Vcomprising a hub 13 and struts 18a, also preferably three' in number.

Mounted coaxially in the engine and supported. by the spiders i7 and i8 is a tube assembly 19. Located on this' tube assembly is a control element 26 generally disc shaped and including leaf valves 2da. As will. be noted hereinafter the unit 21@ acts as the intake valve during pulse-jet engine operation. and as a llame holder during ram-jet operation.

ln an undercut on tube 19 is a fuel ejector vZiand pilot llame or igniter Z2. As shown in the figure the ena gine is in the pulse-jet modeof operation and thisv mode will now be briefly described.

After fuel has been injected into the chamber 41 via fuel line 36 which is routed through tube 19, and has been mixed with air, the operation of igniter 212 vialead 3S, similarly routed, causes combustion. As a result, products of combustion are `propelled with great energy towards the exhaust section. Expansion upstream' or towards the intake section 1i 'is prevented by the operation of unilateral pressure-sensitive valve 20; A .i

Asthe gases are ejected froxn'the exhaustY sectioria pressure reduction occurs in the chamber 41 causing the intake of air via inlet 11 and dilfuser 12v through the valve Z0 which is opened in the presence Vof this kreduced p resf sure. Combustion occurs once again and the cyclefref` peints itself. Thus in the puse-jet mode of operation there is periodic combustion which develops a thrust whichv may accordingly be used to provide motive power.

Before proceeding with theram-jetmode of operation, reference may be had to FIGURE 2 where the details of the control element 20 are shown. As may be observed in the figure a series of valve leafs 20a are arranged in a louvered manner, each leaf being pivotal such that when swung outward in a longitudinal direction the passage of air is permitted while the valve bank is closed when the leafs are returned downward to their normal position of rest.

As may be seen in FIGURES 1 and 2 the entire assembly 26 has mounted thereon struts 25, one end of each being secured to the control valve 20 and the other end being secured to actuator rod 26. As may be seen in FIGURE 1 this actuator rod 26 is a component of a hydraulic linear actuator 28. Each actuator includes a cylinder 3d, control unit 29 and associated hydraulic lines 31 to 3d. These actuators are well known to the art and are frequently used in aviation equipment by virtue of their reliability and high power-to-weight ratio.

As is evident from FIGURE l, operation of the actuators causes a longitudinal translation of the rods 26 and a corresponding translation of the control element 20 which is secured thereto. Thus, the control element which is secured to hub 23 may be displaced in a longitudinal direction along the tube 19, and in the dashed line position in FIGURE 1 provides high-speed ram jet operation with the control unit now acting as a flame holder. The linear actuator 28 may be controlled manually and/o1' automatically at a predetermined speed.

When operative as a ram jet, continuous combustion occurs, being supplied with air from inlet 11, fuel from apertures 21 and ignition from element 22. The latter may be a spark plug, glow plug or other similar device. A continuous thrust is developed and motive power at high speeds is thus provided.

With control unit 20 in the aft or ram position the pressure differential across the unit is such as to cause the valve leafs 20a to remain open, thus providing a stable combustion.

In the process of transition it is noted that control element 20, and specifically the hub 23, slides over and closes of the fuel ejection orifices 21, thus temporarily cutting off combustion during the transition phase. Thus cut-off persists until the hub 23 has also cleared the igniter 22, after which combustion again resumes.

In addition to the usual methods of controlling engine performance, as for example by manually or automatically displacing centerbody 50 longitudinally, the engine of FIGURE 1 may be controlled by adjusting, over a narrow range, the position of the control unit 20. In the pulsejet mode of operation this is equivalent to providing an adjustable bleed flowing between the intake valve 20 and surface 13, and in the ram-jet mode of operation this is equivalent to adjusting the position of the flame holder to alter the character of flame propagation and combustion.

While a specific engine configuration has been shown in the drawings including the location of constrictions, fuel injector and igniter, and valve assembly arrangement, it is intended that these be construed as exemplary only since there are diverse variations known to the art. Thus, the longitudinal profile of the duct which characterizes the internal passageway of the engine may be altered in accordance with design requirements. Similarly, other valve bank arrangements may be used especially in view of known difficulties with these members and the need for carefully designing them in accordance with expected operating conditions. Also, different locations for the fuel igniter and fuel injector may be desirable and auxiliary injectors and igniters may be provided to maintain, for example, limited combustion during the transition from one operating configuration to the other.

The invention in its broader aspects is not limited to the specific mechanisms shown and described but departures may be made therefrom within the scope of the accompanying claims without departing from the principles of the inventions and without sacrificing its chief advantages.

What is claimed is:

1. A jet propulsion device comprising a streamlined housing, an inlet aperture at one end of said housing, an exhaust outlet at the other end of said housing, a combustion chamber in said housing including a fuel injector and igniter, a displaceable control unit slidably mounted on a centrally located longitudinally extending tube in said housing, said unit when'in a first position adjacent said inlet aperture comprising inlet valve means and when in a second position displaced from said first position towards said exhaust outlet comprising flame holding means, said unit including a plurality of movable elements operable to control the passage of a gas therethrough, and also in cluding a section which overlaps and encloses said fuel injector at a position of said control unit intermediate said first and second positions, control unit actuator means, control displacement means coupled to said control unit and responsive to said actuator means for controlling the longitudinal displacement of said control unit from said first position to said second position whereby said control unit may be operated as a unilateral intake valve or a flame holder thus providing pulse jet or ram jet operation respectively.

2. A jet propulsion device comprising a streamlined housing, an inlet aperture at one end of said housing, an exhaust outlet at the other end of said housing, a com bustion chamber in said housing including a fuel injector and igniter, a displaceable control unit slidably mounted on a centrally located longitudinally extending tube in said housing, said unit when in a first position adjacent said inlet aperture comprising inlet valve means and when in a second position displaced from said first position towards said exhaust outlet comprising ame holding means, said unit including a plurality of movable elements opera ble to control the passage of a gas therethrough, and also including a section which overlaps and encloses said igniter at a position of said control unit intermediate said first and second positions, control unit actuator means, control displacement means coupled to said control unit and responsive to said actuator means for controlling the longitudinal displacement of said control unit from said first position to said second position whereby said control unit may be operated as a unilateral intake valve or a flame holder thus providing pulse jet or ram jet operation respectively.

References Cited in the file of this patent UNITED STATES PATENTS 2,683,961 Britton et al July 20, 1954 2,850,872 Stockbarger et al Sept. 9, 1958 2,867,977 Buck Jan. 13, 1959 FOREIGN PATENTS 1,022,912 Germany Jan. 16, 1958 

1. A JET PROPULSION DEVICE COMPRISING A STREAMLINED HOUSING, AN INLET APERTURE AT ONE END OF SAID HOUSING , AN EXHAUST OUTLET AT THE OTHER END OF SAID HOUSING, A COMBUSTION CHAMBER IN SAID HOUSING INCLUDING A FUEL INJECTOR AND IGNITER, A DISPLACEABLE CONTROL UNIT SLIDABLY MOUNTED ON A CENTRALLY LOCATED LONGITUDINALLY EXTENDING TUBE IN SAID HOUSING, SAID UNIT WHEN IN A FIRST POSITION ADJACENT SAID INLET APERTURE COMPRISING INLET VALVE MEANS AND WHEN IN A SECOND POSITION DISPLACED FROM SAID FIRST POSITION TOWARDS SAID EXHAUST OUTLET COMPRISING FLAME HOLDING MEANS, SAID UNIT INCLUDING A PLURALITY OF MOVABLE ELEMENTS OPERABLE TO CONTROL THE PASSAGE OF A GAS THERETHROUGH, AND ALSO INCLUDING A SECTION WHICH OVERLAPS AND ENCLOSURES SAID FUEL INJECTOR AT A POSITION OF SAID CONTROL UNIT INTERMEDIATE SAID FIRST AND SECOND POSITION CONTROL UNIT ACTUATOR MEANS, CONTROL DISPLACEMENT MEANS COUPLED TO SAID CONTROL UNIT AND RESPONSIVE TO SAID ACTUATOR MEANS FOR CONTROLLING THE LONGITUDINAL DISPLACEMENT OF SAID CONTROL UNIT FROM SAID FIRST POSITION TO SAID SECOND POSITION WHEREBY SAID CONTROL UNIT MAY BE OPERATED AS A UNILATERAL INTAKE VALVE OF A FLAME HOLDER THUS PROVIDING PULSE JET OR RAM JET OPERATION RESPECTIVELY. 